Mark Cuban spars with Donald Trump's biggest online broadcaster and a poker legend in a Twitter war

Mark Cuban. Christian Petersen/Getty Images Billionaire businessman Mark Cuban, the Right Side Broadcasting Network, and poker legend Mike Matusow engaged in a lengthy Twitter war Tuesday over the size of the crowd at Donald Trump's Cincinnati rally last week.

It began when Cuban — the owner of the NBA's Dallas Mavericks, star of ABC's "Shark Tank," and a prominent supporter of Democratic nominee Hillary Clinton — tweeted an Instagram photo from the Trump rally. It showed the upper deck of the arena virtually empty.

The video showed the packed lower area but did not give a view of the upper deck Cuban had referenced. Trump himself frequently touts the size of his crowds at the rallies and criticizes media outlets for not panning their cameras to "show the crowd."

"Lots of empty seats and just lower bowl," Cuban responded. "You do realize the video and pic I posted were taken the same time?"

Right Side Broadcasting's account then began engaging, asking Cuban to "find one video" where Clinton "has got 1/5 of this crowd at ANY rally."